Dynamo-electric machine



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DYNAMO ELECTRIC MACHINE.

No. 260,652. Patented July 4, 1882.

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C. F. BRUSH.

DYNAMO ELECTRIC MACHINE.

Patented July 4,'1882l l/V VENTOH A Harney N4 Pneus maumnpw. wmmlm. o. c.

UNITED STATES PATENT OEEICE.

CHARLES F. BRUSH, OF CLEVELAND, OHIO.

DYNAMO-ELECTRIC MACHINE.

SPECIFICATION forming part of Letters Patent No. 260,652, dated July 4, 1882.

Application tiled June 1, 1850.

To all whom it may concern:

Be it known that I, CHARLES F. BRUSH, of Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Improvements in I)ynamo-Eleetric Machines; and I do hereby declare the following to be a' full, clear, and exact description of the invention, such as will enable others skilled in the art to which it pertains to make and use it, reference being had to the accompanying drawings, which-form part of this specification.

My invention relates to dynamo-electric machines, and has for its object the suppression to a considerable extent ofthe extra current77 induced in the helices ot' the iieldof-force magnets of such machines when from any cause lluctuations ot' magnetic intensity occur. The advantages arising from the suppression of this extra current obtain with dynamo-electric machines of all capacities and in all applications, but are more especially prominent in those machines Which are adapted to produce currents of high electromotive force and considerable volume. lhe conspicuous evils attending the presence of the extra current in such machines are danger to the insulation of the apparatus and exaggeration of accidental or unavoidable current iluctuations.

In dynamo-electric machines producing cur rents of high tension the number of convolutions of the helices exciting the field-magnets must be large on account ot' the comparatively small volume of current in circulation. Now, when the current from such a machine is suddenly diminished by sudden increase of resistance io its passa-ge, or when it is stopped altogether by the breaking et' its circuit, the extra current produced by the discharge of the magnetism of the field-magnets and by the inductive action ofthe ditt'erent convolutions of the exciting helices on each other is of very high tension, capableofburstingthrongh heavy insulation or traversing a very considerable air-space. Again, when one or more voltaicare lamps are operated in the circuit oi' a machine a peculiar rythmical fluctuation ot' the current strength, as indicated by corresponding motion in the mechanism of the lamp or lamps, may often be observed, while the speed at which the armature of the machine is rotated remains perfectly constant. By preventing motion ofthe mechanism ofthe lamps for (No model.)

a short time this action may cease, but is liable to appear again upon any disturbance ofthe circuit-resistance. Thus a state of nnstable equilibrium is indicated either in the lamps, dynamo-machine, or both. Although this condition ot' affairs mayobtain in thelamps where it is easily remedied, it may also appear in the machine, as is proven by the success of the remedy applied, consisting in the suppression, as far asis practicable, of the extra current in the held-magnet helices and the absorption ofthe opposing or inverse electro-m0- tive force caused by rising magnetism of the inclosed cores. The exact manner in which the elimination ot' the inverse and direct currents in the helices ofthe field-magnets due to the rising or falling ofthe magnetism of their cores acts as a remedy for the evil last indicated is not easy to explain. I have developed several theories concerning the phenomenon, but, as noneare entirely satisfactory, I will not state them.

I accomplish my object by surrounding thel `cores ofthe tieldmagnets ot'a dynamo-electricl machine with a continuous band of sheet cop; per or other suitable conductor wound in thel direction ot' the magnetisinghelices. Over;

these bands are coiled the said magnetising helices in the customary manner.

Figure l of the drawings shows this form ot' my invention. Figs. 2, 3, 4 show various moditications of thc same. Fig. 5 illustrates a dynamo machine provided with my improvement.

In Fig. l, A is the iron core of one of the eld-magnets of a dynamo-electric machine.

B is a tube, of copper or other suitable com ductor, surrounding the core A.

C is the usual magnetising-helix.

The function of the tube or envelope B in affording a free path for both the inverse and direct currents, due to rising or falling magnetism of the core A, aud thus absorbing the greater part of the inductive influence of the latter, is too obvious to require further expla nation.

Obviously the tube or band B may envelop both core A and helix C, as shown in Fig. 2, or it may inclose a portion only of the helix, as shown in Fig. 8. i

For the purpose of further absorbing the inverse and direct currents induced directly by IOO rising or falling currents in the helix itself, several conductors, B, may be arranged between the various layers of the helix-wire (l, as shown in Fig. 4.

Instead ot' a conducting tube or band, B, a layer of wire with its ends joined may be ernployed, or lthe core A may be wound with two or more helices in any manner, one or more ot said helices having its ends joined.

What l claim is- 1. In a dynamo-electric machine, the combi- -nation, with the moving coils or bobbins ot' conductors, of eld-of-force magnets having their cores encircled by one or more closed conductors, substantially as set forth.

2. In a dynamo-electric machine, the combination of the moving coils or bobbins ot' conductor Within .which the electric current is induced and one or more eld-of-t'orce electromagnets that are surrounded by one or more scribing witnesses. Y

CHA RLES F. BRUSH. Witnesses:

J No. CRoWELL, Jr., LEVERETT L. LEGGETT.

Ytethis specification in the presence of two sub- 3 5 

